Can't hear anything through headphones

[silvervajra@gmail.com]

My network is set up correctly; I can get into a session. The other person in the session can hear both of us. I can't hear either of us. I can't actually hear any audio, although the signal shows up visually on the VU meters. I use a Mac, and my audio output is set up correctly there. I can hear audio through the phones with no problem using other software. I have run out of things to try. Please help!